There have hitherto been provided a variety of terminals to be pressure-welded with an electrical wire, for use in a connector to connect the electrical wire.
Examples of such terminals include a terminal 103 in which an electrical wire 6 is pressed into an insertion part 102 provided with a U-shaped insertion groove 101 shown in FIG. 16(A). This terminal 103 was subjected to stress analysis of confirming a location of stress concentration and an amount of plastic deformation that occurs by a load by pressing the electrical wire 6 into the insertion part 102. It was found according to this stress analysis that stress concentrates on a region S.
Stress F1 concentrated on this region S specifically acts on each side of an end 104 of the insertion groove 101 which is curved in a U-shape, as shown in FIG. 17(A). The stress F1 can be decomposed into a horizontal component Fx and a vertical component Fy. Then, as shown in FIG. 17(B), this vertical component Fy is synthesized with a vertical component of stress F2 which is generated at the time of pressing an electrical wire 6 into the insertion groove 101, and stress is thus concentrated on an end 104.
FIG. 16(B) shows a result of the analysis of confirming the amount of plastic deformation, graphically representing a curve L indicative of the relation between the load applied to the insertion part 102 and the displacement amount thereby. Further, a straight line M in FIG. 16(B) is indicative of the relation between the applied load and the displacement amount with the insertion part 102 in an elastically deformed state. It is to be noted that the elastically deformed state refers to that the curve L is in a region of a straight line passing an origin, and this region is referred to as an elastic deformation region. The insertion part 102 of the terminal 103 is elastically deformed with the applied load up to a point P, but it is plastically deformed when the load further increases. For this reason, when the pressed-in electrical wire 6 is pulled out in a state where the applied load has reached a point Q, the insertion part 102 gets back along a straight line N parallel to the straight line M, to reach a point R. It was found from the above that this insertion part 102 is plastically deformed by pressing-in of the electrical wire 6.
As a terminal having the above configuration, a pressure-welding connector terminal, which is connected with an electrical wire via an insertion part provided with a U-shaped slit similarly to the above, is described in Japanese Unexamined Patent Publication No. H9-312106.
However, in the terminal described in this publication, the U-shaped slit is just provided in a platy insertion part and the insertion part is thus apt to be plastically deformed in the case of pressing an electrical wire into the U-shaped slit, thus leading to a decrease in force of holding the electrical wire. There has thus been a problem of poor repairability at the time of reinserting and using the electrical wire.
Further, when the strength of the insertion part is enhanced for ensuring predetermined force of holding the electrical wire, spring force of the insertion part needs increasing, thus causing a problem of making the U-shaped slit difficult for pressing-in of the electrical wire.